Young people caught with small amounts of drugs for their own use should not receive criminal convictions, Nick Clegg will say today.

In a speech alongside Virgin owner Sir Richard Branson, the Deputy Prime Minister will attack the "ludicrous" status quo that allows people to be unable to get work in later life if they make a "youthful mistake".

He will announce Liberal Democrat proposals to take users out of the criminal justice system, instead introducing either treatment, education or a civil fine for those caught in possession of drugs for personal use.

Under current rules, someone cautioned for such a crime would have to declare it for six years when applying for certain jobs.

If they are fined for the same offence that increases to 11 years, while it will have to be declared for the rest of their lives if they receive a prison sentence.

The chief executive of Virgin Galactic has said "space is hard and today was a tough day" after the company's SpaceShipTwo crashed in the Mojave desert during a test flight, killing one of the two pilots on board.

"We are going to be supporting the investigation as we figure out what happened today and we're going to get through it," George Whiteside said at a news conference at the Mojave Air and Space Port in California.

Mr Whiteside confirmed Virgin chief Sir Richard Branson would be arriving to join the team on Saturday morning local time.

"The future rests in many ways on hard days like this," he added. "But we believe we owe it to the folks who are flying these vehicles and the folks who have been working so hard on them to understand this and move forward, which is what we'll do."

The entrepreneur was speaking at the Scottish Business Awards in Edinburgh last night, in front of an audience of 2,000 guests, including First Minister Alex Salmond.

ITV News' Alastair Stewart hosted a question-and-answer session with Sir Richard and asked him if he thought Scotland's famous entrepreneurial track record could be better maintained as part of the UK or under independence.

The billionaire received a round of applause from the audience when he said: "I had a feeling this was going to come up. I'm not sure it's my place to intervene and I know that's a cop out.

"I'm coming to the Commonwealth Games, maybe by then I'll say something."